Isn't A highspin? t2g(3). Pairing cannot take place before 4 electrons. Am I wrong?

Arre exactly man same thought

@Yash_Srivastava2 D is out of the question as you know
A is high spin. There are only 3 electrons they go in the first 3 orbitals, no pairing.
B is diamagnetic. En is a SFL
Rh 3+ is 4d6. Pairing occurs
C is the only option that matches.